The present invention relates to removal and concentration of organic vapors from gas streams. More particularly, this invention concerns economically concentrating and removing organic vapors from large volumes of gas containing low concentrations of organic vapors. Furthermore, the present invention can be used at any pressure and can be applied to both the pollution control and gas processing industries.
Much of the industrial air pollution that exists today is attributable to the emission of large volumes of gas contaminated with organic vapors at very low concentrations. An economical method of destroying the organic contaminants by incineration has been described in my U.S. Pat. No. 3,455,089 issued July 15, 1970 entitled "Process For Removing Organic Contaminants From Air". Also, an economical method of recovering these contaminants has been described in my U.S. Pat. No. 3,534,529 issued Oct. 20, 1970 entitled "Process For Recovering Organic Vapors From Air Streams". The two processes described in these patents involve cyclic operations and therefore could not provide the economy and flexibility of the continuous process described in my U.S. Pat. No. 4,231,764 issued Nov. 4, 1980 entitled "System For Removing Organic Contaminants From Air". The process of this patent utilizes a multi-stage fluid bed adsorption system; one stage for countercurrent adsorption, two or more stages for regeneration and one stage for cooling. While this process offered many advantages over previous processes, it also presented disadvantages which limited its acceptance in industry. These diadvantages included the high energy cost to maintain fluidization of the adsorbent, gradual attrition of the fluidized adsorbent, inability to process varying flow streams and the limiting vapor velocity required to avoid entrainment of the adsorbent.
A solvent concentrating system utilizing a rotating adsorbent bed is described in Bulletin 11B3 of Met-Pro Corporation, Harleysville, Pa.
Heretofore, it has been most difficult to recover organic contaminants from gases when they are present in low concentrations. Known processes require high investment and/or operating costs. Additionally, the excessive energy requirements for regeneration make many of these processes prohibitive.